Thank you for making yourselves available. I have a an '84 Grand Marquis 302.
The car has had the same problem for months and all the new parts have not changed the problem one bit. The valves ping under a load or hard acceleration. The engine has a slight miss at idle or any speed (hot or cold). The miss is not with every revolution of the engine. It is just every now and then. My mecanic plugged it to a diagnostic machine and it said it was the new EGR valve. We replaced the new EGR with a newer one. Still the same. I used a blank off plate but this depressed or forced the valve to be pushed open (this was with the older EGR valve) and the computer knew the valve was open. The car would not run at all so I unplugged the pigtail on the EGR and the car ran exactly the same as it always had been. I removed the blankoff plate and installed the new EGR. The car still runs the same as if the old EGR valve was on it or as if the EGR was unplugged.
I removed the base plate and there is no carbon buildup or blocking of the EGR passages. I have checked for a vacuum leak even under the dash. I have a long list of new parts but nothing has changed or effected the original problem one bit.
I have a new exhaust system. I installed a new smog system including the cross over on the back of the heads. New O2 sensor. New fuel filter. New air filter. New PVC valve and filter element. New plugs, wires, cap and button. New alternator.
This is a 302 (5.0) factory rebuilt engine. It was installed 10 years ago. I am the only owner and driver of this car. I have maintained this engine extremely well. The car starts fine and runs fine but there is always that annoying miss (like a hickup) and the car has no power. If you really "get on it" all you hear is valve rattling. On long hills on the interstate I start loosing speed and you can hear the valves floating.
My mechanic says there are no codes other than the EGR. I replaced a new EGR with another new EGR. He charged me $100.00 to tell me it was the EGR. I do not want to pay him $100.00 more to tell me the car still has the same problem it had before I gave him the money. I guess, as long as I have money, he will keep guessing that it is something new that I have already replaced. I know that new parts can be faulty but I am thinking it is a flaw in the brain box. Do these cars have a history of having a malfunction in the Engine Controller? Hey, if my mechanic can guess, so can I.
Please respond if you have any idea what the remedy could be. Nice car. She is my baby but my baby is sick.
Thankx, Rob'

Pour 2 bottles of rubbing alcohol in the gas tank and fill it to the rim with gas that you get somewhere other than your regular filling station. Then run it for a few days and then get back with us and let us know how it is reacting. Do this before putting any more money into it.We will eliminate the simple things first. Good luck!!

Pour 2 bottles of rubbing alcohol in the gas tank and fill it to the rim with gas that you get somewhere other than your regular filling station. Then run it for a few days and then get back with us and let us know how it is reacting. Do this before putting any more money into it.We will eliminate the simple things first. Good luck!!

OK but you have to give me a little bit more than that. Why would I be doing that and what is the logic in doing it. I could probably be talked into holding a cat while you skin it but I need to know why first.
Lets say I do what you say, then I blow the engine out the tail pipes, do you get more than a good chuckle?

OK but you have to give me a little bit more than that. Why would I be doing that and what is the logic in doing it. I could probably be talked into holding a cat while you skin it but I need to know why first.
Lets say I do what you say, then I blow the engine out the tail pipes, do you get more than a good chuckle?

I found the problem. The electrical connection to the injectors was rusty and dirty. I cleaned the connection and the car runs like new. I checked the timing and set the idle. It doesn't have the power of a Mustang 5.0 but it never did. My baby is smooth as silk and rides the same way. She might be old but she rides better than a new one. I am sure all the new parts that I bought were necessary but it was really starting to worry me because the valves were floating almost all the time and I couldn't figure it out. Sometimes it is the simplist things that are hiding from plain sight. I am glad I stayed after this until I found the problem. I was determined to find this no matter what. Thanks.

I figured it was a fuel problem(water in the gas) and alcohol will mix with the water and burn where fuel won't mix with water. That causes dead spots in the combustion chambers and therefore valve chatter and no power. The electrical connector to the injectors malfunctioning is essentially the same thing.I wouldn't tell you something to do that would cause catastrophic failure or even a simple malfunction either and would like to think that nobody that uses this forum would either,but,I understand your reasoning. Glad you got it fixed and good luck .